Anatomical laterality of primary intestinal diffuse large B-cell lymphoma independently stratifies survival: New prognostic nomogram incorporating tumor location.

BACKGROUND

Primary intestinal (PI) diffuse large B-cell lymphoma (DLBCL) represents a biologically and clinically heterogeneous subtype of extranodal lymphoma. The international prognostic index (IPI) was originally developed for predominantly nodal DLBCL (N-DLBCL) and inadequately reflected site-specific risk within the intestine. Prompted by colorectal carcinoma where primary tumor laterality (left vs right of the splenic flexure) is prognostically relevant, we raised the question of whether analogous intestinal laterality might influence survival in PI-DLBCL.

AIM: To investigate whether intestinal laterality influences survival in PI-DLBCL and construct a location-integrated prognostic nomogram.

METHODS

We retrospectively analyzed 3832 PI-DLBCL patients (SEER 2002-2021) and externally validated in 107 patients (Sun Yat-sen University Cancer Center 2014-2024). A prognostic nomogram integrating age, Ann Arbor stage, chemotherapy, surgery, and tumor sidedness (left vs right of the splenic flexure) was constructed. To mitigate treatment-selection bias, we additionally performed propensity score matching (PSM) for left- vs right-sided PI-DLBCL.

RESULTS

Left-sided PI-DLBCL was independently associated with inferior overall survival (OS) (hazard ratio = 1.15, P = 0.035) and the association persisted after PSM. When compared with intra-abdominal N-DLBCL, right-sided PI-DLBCL showed superior OS, whereas left-sided PI-DLBCL had worse OS. The nomogram achieved superior discrimination vs the IPI (C-index: 0.749 vs 0.710) and higher time-dependent area under the curves (1-year: 0.865 vs 0.753; 2-year: 0.792 vs 0.731; 3-year: 0.786 vs 0.727) in the external validation cohort. The nomogram stratified patients into low-, median-, and high-risk groups with clear OS separation in both the training and external cohorts.

CONCLUSION

Intestinal laterality is an independent, clinically actionable determinant of survival in PI-DLBCL. The proposed nomogram provides individualized survival prediction and risk stratification and showed higher discrimination than the IPI, supporting the incorporation of tumor anatomical location into prognostic assessment and risk-adapted management.